#include<bits/stdc++.h>
#define ONLINE_JUDGE
#define ll long long
#define ull unsigned long long
using namespace std;

const ll N = 1e5 + 10, INF = 0x3f3f3f3f;

ll n;
ll cnt[N];
vector<pair<ll, ll>> g[N];

ll dfs(ll x, ll fa) {
    ll res = 0;
    for (auto [y, w] : g[x]) {
        if (y == fa) continue;
        res += dfs(y, x);
        cnt[x] += cnt[y];
        res += abs(cnt[y]) * w;
    }
    return res;
}

void solve()
{
    cin >> n;
    for (ll i = 1;i <= n;i++) cin >> cnt[i];
    for (ll i = 1;i < n;i++) {
        ll x, y, w; cin >> x >> y >> w;
        g[x].push_back({ y,w });
        g[y].push_back({ x,w });
    }
    cout << dfs(1, 0);
}

signed main()
{
    // ios::sync_with_stdio(0);
    // cin.tie(0);cout.tie(0);
#ifndef ONLINE_JUDGE
    std::istringstream in(R"()");
    std::cin.rdbuf(in.rdbuf());
#endif
    ll T = 1;
    //cin>>T;
    for (ll i = 1;i <= T;i++) {
        solve();
    }
}